The present invention pertains to a change coupling or interchangeable coupling for detachably fastening tools on manipulators and more particularly to coupling parts and a positive-locking locking mechanism, wherein the locking mechanism has a plurality of movable locking elements, a piston for actuating the locking elements and corresponding holding openings in the coupling parts.
Such a change coupling has been known from DE-A 33 47 423. It comprises two coupling parts, one of which is associated with the manipulator and the other with the tool. The coupling parts are fastened to one another with a positive-locking locking mechanism. This locking mechanism has a plurality of movable locking elements in the form of balls, which are actuated by a conical piston. The piston pushes the balls into a locking position between the two coupling parts. In the retracted position, the piston permits the balls to yield into one cylindrical holding opening, as a result of which the locking connection is released and the two coupling parts can be removed from one another. The other holding opening in the tool-side coupling part is designed as a blind hole of a rounded or conical shape. This design of the holding opening is unfavorable concerning the reliable guiding of and the transmission of forces by the locking balls.
DD-A5 291 505 shows a similar change coupling with an external piston, which is designed as an actuating sleeve. The holding openings have an analogous design and the same problems as in the above-mentioned state of the art.
It is therefore the object of the present invention to provide a better change coupling.
According to the invention, a change coupling or interchangeable coupling is provided for detachably fastening tools to manipulators. The coupling has two coupling parts and a positive-locking locking mechanism. The locking mechanism has a plurality of movable locking elements, a piston for actuating the locking elements and corresponding holding openings in the coupling parts. The holding openings are designed as essentially cylindrical ball channels with an oblique channel axis.
The embodiment of a preferably externally located holding opening as an oblique ball channel offers the advantage that, in conjunction with the locking ball, a better and more reliable locking of the coupling parts is achieved. The forces to be transmitted between the coupling parts are optimally transmitted due to the better-defined contact of the locking elements. An undesired clearance between the coupling parts is avoided. In addition, tolerances and wear are absorbed automatically, and a bevel on the jacket of the piston has a favorable effect due to its clamping function.
Moreover, a cylindrical ball channel has the advantage that linear contact points are obtained, which lead to better guiding and distribution as well as transmission of the clamping forces. The loads and the wear of the locking mechanism are reduced. In addition, the ball channel can be manufactured more easily and accurately than a blind hole. This not only improves the function, but also reduces the manufacturing effort and the cost of the locking mechanism.
The individual distributed recesses on the jacket of the piston offer the advantage that the locking element, especially a ball, can cover greater distances between the locking position and the releasing position. This makes possible a greater coverage and deeper immersion of the ball into the two holding openings in the locking position. The positive locking and the locking are better and withstand higher loads as a result.
The arrangement of the recesses spaced in the circumferential direction offers advantages in terms of the accuracy of the guiding of the piston. Closed jacket surfaces, which offer an accurate guide surface, are left between the recesses.
It is advantageous for centering and guiding the locking elements, especially the balls, to design the recesses as a secant-like flattened area on the cylinder jacket. The locking elements are better guided by the piston as a result, and the tolerances for the rotation position of the piston can also be lower.
Bevels, which exert a tensioning force on the locking elements in the direction of the holding openings during the closing of the locking mechanism, may be arranged under the recesses.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.